it means, the device, haven't any PIN password.

just do this :

Goto Settings > LockScreen > Screen Lock

and set the password for PIN and after this, try again for backup and it showing you for enter the PIN password and then, Backup process will be starting.

good day.

it means, the device, haven't any PIN password.

just do this :

Goto Settings > LockScreen > Screen Lock

and set the password for PIN and after this, try again for backup and it showing you for enter the PIN password and then, Backup process will be starting.

Edit :

after Set the PIN, use this Command :

adb backup -all

this command will be show to you the windows like this :

it means, you haven't any PIN password.

just do this :

Goto Settings > LockScreen > Screen Lock

and set the password for PIN and after this, try again for backup and it showing you for enter the PIN password and then, Backup process will be starting.

good day.

it means, the device, haven't any PIN password.

just do this :

Goto Settings > LockScreen > Screen Lock

and set the password for PIN and after this, try again for backup and it showing you for enter the PIN password and then, Backup process will be starting.

good day.